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To: internals@lists.php.net,Dmitry Stogov <dmitry@php.net>
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Date: Tue, 07 Nov 2006 12:08:13 +0100
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Subject: Re: [PATCH] =& doesn't remove "old" references like unset()
From: mike@php.net (Michael Wallner)

Matt Wilmas wrote:
> Hi (Dmitry?),
> 
> See Bug #33282 -- I saw it in the Bug Summary; don't know if there are other
> related ones...  Same applies to foreach ($arr ... &$v) which is where I
> noticed it last week with var_dump($arr).  All elements that WERE referenced
> but aren't anymore still have is_ref=1 (when refcount=1).  Only the last
> referenced element should be a reference (unless the others were to begin
> with).  unset()'ing the reference variable removes the reference from the
> last element.  Example:
> 
> $a = array(1, 2, 3);
> $r = &$a[0];
> $r = &$a[1];
> $r = &$a[2];
> var_dump($a);
> 
> array(3) {
>   [0]=>
>   &int(1)
>   [1]=>
>   &int(2)
>   [2]=>
>   &int(3)  // unset($r) will take care of this one
> }
> 
> The reference (&) should no longer be on the first 2 elements, right?
> Setting is_ref=0 when refcount=1 in zend_assign_to_variable_reference()
> fixes it.  I assume it won't cause other problems since the same thing is
> done in zval_ptr_dtor(). :-)
> 

This looks like it may actually fix a lot of previously bogus'ed bug reports?

> 
> ------------------------------------------------------------------------
> 
> Index: zend_execute.c
> ===================================================================
> RCS file: /repository/ZendEngine2/zend_execute.c,v
> retrieving revision 1.752
> diff -u -r1.752 zend_execute.c
> --- zend_execute.c	2 Oct 2006 11:05:02 -0000	1.752
> +++ zend_execute.c	7 Nov 2006 05:24:38 -0000
> @@ -438,6 +438,8 @@
>  		if (variable_ptr->refcount==0) {
>  			zendi_zval_dtor(*variable_ptr);
>  			FREE_ZVAL(variable_ptr);
> +		} else if (variable_ptr->refcount == 1) {
> +			variable_ptr->is_ref = 0;
>  		}
>  	} else if (!variable_ptr->is_ref) {
>  		if (variable_ptr_ptr == value_ptr_ptr) {
> 
> 
> ------------------------------------------------------------------------
> 
> Index: zend_execute.c
> ===================================================================
> RCS file: /repository/ZendEngine2/zend_execute.c,v
> retrieving revision 1.716.2.12.2.12
> diff -u -r1.716.2.12.2.12 zend_execute.c
> --- zend_execute.c	2 Oct 2006 11:09:52 -0000	1.716.2.12.2.12
> +++ zend_execute.c	7 Nov 2006 05:24:40 -0000
> @@ -415,6 +415,8 @@
>  		if (variable_ptr->refcount==0) {
>  			zendi_zval_dtor(*variable_ptr);
>  			FREE_ZVAL(variable_ptr);
> +		} else if (variable_ptr->refcount == 1) {
> +			variable_ptr->is_ref = 0;
>  		}
>  	} else if (!variable_ptr->is_ref) {
>  		if (variable_ptr_ptr == value_ptr_ptr) {


-- 
Michael